Home / Health & safety

NIOSH lifting equation

Enter weight, distances, trunk twist, frequency and coupling to find the recommended maximum weight for the task, the low-back injury risk and what to change first at the workstation.

Pre-sizing and estimating tool: results do not replace design, calculations or reports signed by a licensed professional, nor verification against the applicable codes and standards.

Check
Load and pace
Origin (where the load is picked up)
Destination (where the load is set down)

Significant control is needed when the load must be placed precisely, guided or held at the destination. The equation applies to two-handed, standing lifts without jerky motion.

—Lifting index (LI)
—

Equation multipliers

Each factor from 0 to 1; the lower it is, the more it cuts the recommended limit.

Tap the chart to see the values.

Recommended limit after fixing each factor

Limit at the critical point if only that factor were brought to ideal (multiplier 1), compared with the current load.

Tap the chart to see the values.

Improvement suggestions

In order of gain, starting from the multipliers that weigh most.

    The report gathers this page's inputs, results, equations, assumptions and references, with fields for project, engineer and revision. In the print dialog, choose Save as PDF.

    Method, assumptions and references

    Equations used

    RWL = LC × HM × VM × DM × AM × FM × CM; LI = load ÷ RWL
    Metric: LC = 23 kg; HM = 25/H; VM = 1 − 0.003 |V − 75|; DM = 0.82 + 4.5/D; AM = 1 − 0.0032 A (H, V, D in cm; H min 25, D min 25)
    US units: LC = 51 lb; HM = 10/H; VM = 1 − 0.0075 |V − 30|; DM = 0.82 + 1.8/D; AM = 1 − 0.0032 A (H min 10, D min 10)
    FM from Table 5 (frequency × duration × V < 30 in at origin); CM from Table 7 (coupling × V < 30 in); multiplier = 0 if H > 25 in, V > 70 in, D > 70 in, A > 135° or F > 15/min

    Assumptions and limits

    • Two-handed, standing, smooth lifts on a non-slip floor in a normal thermal environment. Not valid for one-handed, seated or kneeling lifts, carrying, pushing, pulling or unstable loads.
    • Frequencies between Table 5 rows use the next higher row (conservative); below 0.2 lifts/min, 0.2 is used. In US units the inch formulas of the manual are applied.
    • The destination is evaluated when there is significant control of the load there; the task LI is the larger of the two. Multi-task jobs need the composite index (CLI), not covered here.

    Standards and technical documents

    • Waters, T. R.; Putz-Anderson, V.; Garg, A.; Fine, L. J. Revised NIOSH equation for the design and evaluation of manual lifting tasks. Ergonomics, 36(7), 749–776, 1993
    • Waters, T. R.; Putz-Anderson, V.; Garg, A. Applications Manual for the Revised NIOSH Lifting Equation. DHHS (NIOSH) Publication No. 94-110, 1994
    • ISO 11228-1:2021: Ergonomics — Manual handling — Part 1: Lifting, lowering and carrying
    • EN 1005-2:2003+A1:2008: Safety of machinery — Human physical performance — Part 2: Manual handling of machinery and component parts of machinery

    U.S. regulations

    • OSH Act of 1970, Section 5(a)(1) (General Duty Clause): OSHA has no specific ergonomics standard and cites lifting hazards under this clause
    • OSHA Technical Manual, Section VII, Chapter 1: Back Disorders and Injuries (uses the NIOSH equation)
    • 29 CFR 1904: recording of work-related musculoskeletal disorders

    Frequently asked questions

    What is the maximum weight a worker should lift?

    Under the NIOSH equation, at most 51 lb in ideal conditions: load close to the body at 30 in height, no twisting, good grip and low frequency. In practice the limit drops a lot; the default example gives about 16.5 lb.

    What does a lifting index of 1.5 mean?

    The load is 50% above the recommended limit for that task. Low-back injury risk is increased and the job should be redesigned.

    Does OSHA set a lifting limit?

    No. OSHA has no ergonomics standard; it can cite serious lifting hazards under the General Duty Clause and refers to the NIOSH equation in its Technical Manual.

    How do I cut the risk fastest?

    Attack the lowest multiplier. Bringing the load from 20 in to 10 in from the body doubles HM; removing a 90° trunk twist raises the limit by about 40%.